No need to rebuild. Click on the button that has a little forest of white arrows, then click on one of your curves. A white arrow will appear at one end. Hit the 'F' key to 'Flip' the direction. Now select the two curves for the loft operation.
When you start a loft, these arrows will appear conecting the ends of the curves Rhino has identified as the start points of each curve. Imagine these as the first edge of the surface it is going to generate. If these points DON'T correspond, you will get a twisted loft. Rhino is very good at telling you what it is proposing to do, so watch the screen, and read the command line as you work.
This usually happens when you draw one curve from left to right, the next from right to left. Rhino will usually sort this out, but sometimes there is no obvious 'right' way and that is the result. 'Direction' also affects surfaces, and you can use the same tool to check which is the 'inside' or the 'outside' of a surface. This affects the way surfaces unroll, so it is worth getting to know this command; it is VERY useful!
Sukhoi tutorial covers this in some detail, by the way.
Tim P